scholarly journals Mechanical factors contributing to the Venus flytrap’s rate-dependent response to stimuli

2021 ◽  
Author(s):  
Eashan Saikia ◽  
Nino F. Läubli ◽  
Hannes Vogler ◽  
Markus Rüggeberg ◽  
Hans J. Herrmann ◽  
...  
Keyword(s):  
Fluid Transport ◽  
Angular Displacement ◽  
Mechanical Stimulus ◽  
Cellular Level ◽  
Sensory Cells ◽  
Mechanical Stimuli ◽  
Multi Scale ◽  
Rate Dependent ◽  
Dionaea Muscipula ◽  
Mechanical Factors

AbstractThe sensory hairs of the Venus flytrap (Dionaea muscipula Ellis) detect mechanical stimuli imparted by their prey and fire bursts of electrical signals called action potentials (APs). APs are elicited when the hairs are sufficiently stimulated and two consecutive APs can trigger closure of the trap. Earlier experiments have identified thresholds for the relevant stimulus parameters, namely the angular displacement $$\theta $$ θ and angular velocity $$\omega $$ ω . However, these experiments could not trace the deformation of the trigger hair’s sensory cells, which are known to transduce the mechanical stimulus. To understand the kinematics at the cellular level, we investigate the role of two relevant mechanical phenomena: viscoelasticity and intercellular fluid transport using a multi-scale numerical model of the sensory hair. We hypothesize that the combined influence of these two phenomena and $$\omega $$ ω contribute to the flytrap’s rate-dependent response to stimuli. In this study, we firstly perform sustained deflection tests on the hair to estimate the viscoelastic material properties of the tissue. Thereafter, through simulations of hair deflection tests at different loading rates, we were able to establish a multi-scale kinematic link between $$\omega $$ ω and the cell wall stretch $$\delta $$ δ . Furthermore, we find that the rate at which $$\delta $$ δ evolves during a stimulus is also proportional to $$\omega $$ ω . This suggests that mechanosensitive ion channels, expected to be stretch-activated and localized in the plasma membrane of the sensory cells, could be additionally sensitive to the rate at which stretch is applied.

scholarly journals Kinematics Governing Mechanotransduction in the Sensory Hair of the Venus flytrap

2020 ◽  
Vol 22 (1) ◽  
pp. 280
Author(s):  
Eashan Saikia ◽  
Nino F. Läubli ◽  
Jan T. Burri ◽  
Markus Rüggeberg ◽  
Christian M. Schlepütz ◽  
...  
Keyword(s):  
Cell Wall ◽  
Cell Shape ◽  
Electrical Response ◽  
Mechanical Stimulus ◽  
Sensory Cells ◽  
Multi Scale ◽  
Venus Flytrap ◽  
Dionaea Muscipula ◽  
Hair Model ◽  
Touch Stimulus

Insects fall prey to the Venus flytrap (Dionaea muscipula) when they touch the sensory hairs located on the flytrap lobes, causing sudden trap closure. The mechanical stimulus imparted by the touch produces an electrical response in the sensory cells of the trigger hair. These cells are found in a constriction near the hair base, where a notch appears around the hair’s periphery. There are mechanosensitive ion channels (MSCs) in the sensory cells that open due to a change in membrane tension; however, the kinematics behind this process is unclear. In this study, we investigate how the stimulus acts on the sensory cells by building a multi-scale hair model, using morphometric data obtained from μ-CT scans. We simulated a single-touch stimulus and evaluated the resulting cell wall stretch. Interestingly, the model showed that high stretch values are diverted away from the notch periphery and, instead, localized in the interior regions of the cell wall. We repeated our simulations for different cell shape variants to elucidate how the morphology influences the location of these high-stretch regions. Our results suggest that there is likely a higher mechanotransduction activity in these ’hotspots’, which may provide new insights into the arrangement and functioning of MSCs in the flytrap.

scholarly journals The Venus flytrap trigger hair–specific potassium channel KDM1 can reestablish the K+ gradient required for hapto-electric signaling

PLoS Biology ◽  
2020 ◽  
Vol 18 (12) ◽  
pp. e3000964
Author(s):  
Anda L. Iosip ◽  
Jennifer Böhm ◽  
Sönke Scherzer ◽  
Khaled A. S. Al-Rasheid ◽  
Ingo Dreyer ◽  
...  
Keyword(s):  
Hair Cells ◽  
Prey Capture ◽  
Dominant Role ◽  
Carnivorous Plant ◽  
Sensory Cells ◽  
Mechanical Stimuli ◽  
Plant Structure ◽  
Dionaea Muscipula ◽  
Selective Channel ◽  
Transcriptional Induction

The carnivorous plant Dionaea muscipula harbors multicellular trigger hairs designed to sense mechanical stimuli upon contact with animal prey. At the base of the trigger hair, mechanosensation is transduced into an all-or-nothing action potential (AP) that spreads all over the trap, ultimately leading to trap closure and prey capture. To reveal the molecular basis for the unique functional repertoire of this mechanoresponsive plant structure, we determined the transcriptome of D. muscipula’s trigger hair. Among the genes that were found to be highly specific to the trigger hair, the Shaker-type channel KDM1 was electrophysiologically characterized as a hyperpolarization- and acid-activated K+-selective channel, thus allowing the reuptake of K+ ions into the trigger hair’s sensory cells during the hyperpolarization phase of the AP. During trap development, the increased electrical excitability of the trigger hair is associated with the transcriptional induction of KDM1. Conversely, when KDM1 is blocked by Cs+ in adult traps, the initiation of APs in response to trigger hair deflection is reduced, and trap closure is suppressed. KDM1 thus plays a dominant role in K+ homeostasis in the context of AP and turgor formation underlying the mechanosensation of trigger hair cells and thus D. muscipula’s hapto-electric signaling.

The initiation of nerve impulses by mesenteric Pacinian corpuscles

1950 ◽  
Vol 137 (886) ◽  
pp. 96-114 ◽  
Keyword(s):  
Conditioning Stimulus ◽  
Mechanical Stimulus ◽  
Constant Current ◽  
Mechanical Stimuli ◽  
Pacinian Corpuscles ◽  
Nerve Impulses ◽  
A Value ◽  
Test Shock ◽  
Long Duration ◽  
Refractory State

A preparation of a single Pacinian corpuscle in the cat’s mesentery has been used to study the initiation of nerve impulses in sensory endings. The minimum movement of a mechanical stimulator required to excite a single corpuscle has been found to be 0⋅5 μ in 100 μ sec. It has been difficult to produce repetitive discharges with rectangular pulses of long duration, either mechanical or of constant current. The latency between a mechanical stimulus and the initiation of an impulse has a value around 1⋅5 msec, for threshold stimuli, and this decreases to a minimum value around 0⋅5 msec, as the stimulus is increased; it is altered only slightly, if at all, by changes in the duration of the maintained displacement of the mechanical stimulator. Subthreshold mechanical stimuli have been shown to facilitate stimulation by electrical test shocks. The return of excitability at the ending is independent of the nature of the conditioning stimulus and varies but little with the nature of the test shock. The value of the latency at threshold is unaffected by the relatively refractory state. The relations of these results to various hypotheses are discussed, and it is suggested that these results can all be accounted for in terms of the known properties of axons.

Rapid Contractions and Associated Potentials in a Sand-Dwelling Anemone

1969 ◽  
Vol 51 (2) ◽  
pp. 513-528
Author(s):  
PETER E. PICKENS
Keyword(s):  
Maximum Size ◽  
Mechanical Stimulus ◽  
Retractor Muscle ◽  
Mechanical Stimuli ◽  
Nerve Impulses ◽  
Electrical Potentials ◽  
Spread Of Excitation ◽  
Electrical Stimuli ◽  
Withdrawal Response ◽  
Muscle Potential

1. Two kinds of electrical potentials can be recorded from the surface of the. retractor muscle of the anemone, Calamactis, during rapid contraction. These are large muscle action potentials and smaller pulses which are thought to be nerve spikes The latter resemble nerve impulses of higher organisms in that they are all-or-none and of short duration. 2. A nerve spike follows each of a pair of electrical stimuli, but the muscle potential and contraction occur only after the second shock, indicating that facilitation is required at the neuromuscular junction. 3. The size of the muscle potential and of the contraction are correlated with the interval between paired electrical stimuli. Maximum size is reached when stimuli are zoo msec. apart even though the minimum effective interval is 30 msec. 4. A muscle potential precedes contraction only along the upper part of the retractor muscle and this is the part that contracts rapidly during the withdrawal response. The lower retractor does not contract. 5. Conduction velocity along the upper retractor is higher than along the lower. The histological correlate of rapid conduction is a nerve net with large, long, longitudinally oriented fibres. 6. The refractory period of the conducting system of the upper retractor is shorter than that of the lower retractor. Consequently, spread of excitation toward the aboral end is limited if paired stimuli are further apart than 250-300 msec. 7. A mechanical stimulus which is just strong enough to elicit a withdrawal response evokes a single muscle potential of maximum size, suggesting that two nerve impulses closer together than 200 msec. precede the muscle potential. Stronger mechanical stimuli evoke a burst of muscle potentials.

Mechanical factors influencing response of joint afferent neurons from cat knee

1975 ◽  
Vol 38 (6) ◽  
pp. 1473-1484 ◽  
Author(s):  
P. Grigg
Keyword(s):  
Mechanical Stimulation ◽  
Angular Displacement ◽  
Afferent Neurons ◽  
Factors Influencing ◽  
Mechanical Factors ◽  
Stimulation Of

The responses of 67 slowly adapting joint afferent neurons in cat posterior articular nerve (PAN) were studied in relation to mechanical stimulation of the knee. The response of most neurons could be interpreted in terms of the stretching of joint tissues resulting from angular displacement of the knee. No neurons discharged at angles intermediate between the limits of movement of the joint. The limits of movement of the joint were operationally defined in terms of displacements resulting from applied torques.

Characteristic dimensionless numbers in multi-scale and rate-dependent processes

2003 ◽  
Vol 1 (1) ◽  
pp. 7-12 ◽  
Author(s):  
Yilong Bai ◽  
Mengfen Xia ◽  
Haiying Wang ◽  
Fujiu Ke
Keyword(s):  
Dimensionless Numbers ◽  
Multi Scale ◽  
Rate Dependent ◽  
Dependent Processes

Respiration-dependent Movements of the Column of Stylidium gvaminifolium

1981 ◽  
Vol 8 (1) ◽  
pp. 45 ◽  
Author(s):  
G.P Findlay ◽  
N Findlay
Keyword(s):  
Refractory Period ◽  
Angular Displacement ◽  
Metabolic Energy ◽  
Original Position ◽  
Firing Process ◽  
Mechanical Stimuli ◽  
Anaerobic Conditions ◽  
Absolute Refractory Period ◽  
Refractory Periods ◽  
Graded Responses

The column of the trigger plant, Stylidium graminifolium, when fully set responds to mechanical stimuli by flipping through an angle of about 4 radians in a fast firing movement lasting about 15-30 ms, and then slowly resetting to its original position in about 400 s. After resetting there is an absolute refractory period of about 500 s during which no further response to stimuli can be initiated, followed by a relative refractory period when graded responses increasing in rate and magnitude with time can be obtained. The resetting movement and the process, occurring during the refractory period, allowing subsequent firing to occur, are inhibited when the air surrounding the column is replaced by nitrogen. The firing movement, however, is not affected by these anaerobic conditions. Thus the firing movement is caused by passive physical forces, rapidly utilizing potential energy from a store built up during the previous resetting and refractory periods. Removal of the labellum, which the column touches when set, causes the column to oscillate with amplitude of about 3-3.5 radians and period of 1-2 ks. When the column is held at a constant angular displacement it develops an oscillatory torque with similar period. These oscillations are inhibited at all stages of the cycle by anaerobic conditions. It appears that the oscillatory behaviour is not a slowed-down firing process followed by normal resetting, but is linked throughout the cycle to the metabolic energy supply.

Murine colonic mucosa hyperproliferation. I. Elevated CFTR expression and enhanced cAMP-dependent Cl−secretion

2000 ◽  
Vol 278 (5) ◽  
pp. G753-G764 ◽  
Author(s):  
Shahid Umar ◽  
Jason Scott ◽  
Joseph H. Sellin ◽  
William P. Dubinsky ◽  
Andrew P. Morris
Keyword(s):  
Cystic Fibrosis ◽  
Fluid Transport ◽  
Cellular Proliferation ◽  
Neck Region ◽  
Anion Channel ◽  
Cellular Level ◽  
Cystic Fibrosis Gene ◽  
Mrna And Protein Expression

Fluid transport in the large intestine is mediated by the cystic fibrosis gene product and cAMP-dependent anion channel cystic fibrosis transmembrane conductance regulator (CFTR). cAMP-mediated Cl−secretion by gastrointestinal cell lines in vitro has been positively correlated with the insertion of CFTR into the apical membrane of differentiated senescent colonocytes and negatively correlated with the failure of CFTR to insert into the plasma membrane of their undifferentiated proliferating counterparts. In native tissues, this relationship remains unresolved. We demonstrate, in a transmissible murine colonic hyperplasia (TMCH) model, that (8-fold) colonocyte proliferation was accompanied by increased cellular CFTR mRNA and protein expression (8.3- and 2.4-fold, respectively) and enhanced mucosal cAMP-dependent Cl−secretion (2.3-fold). By immunofluorescence microscopy, cellular CFTR expression was restricted to the apical pole of cells at the base of the epithelial crypt. In contrast, increased cellular proliferation in vivo led to increases in both the cellular level and the total number of cells expressing this anion channel, with cellular CFTR staining extending into the crypt neck region. Hyperproliferating colonocytes accumulated large amounts of CFTR in apically oriented subcellular perinuclear compartments. This novel mode of CFTR regulation may explain why high endogenous levels of cellular CFTR mRNA and protein within the TMCH epithelium were not matched with larger increases in transmucosal CFTR Cl−current.

Parallel processing of tactile information in the cerebral cortex of the cat: effect of reversible inactivation of SI on responsiveness of SII neurons

1992 ◽  
Vol 67 (2) ◽  
pp. 411-429 ◽  
Author(s):  
A. B. Turman ◽  
D. G. Ferrington ◽  
S. Ghosh ◽  
J. W. Morley ◽  
M. J. Rowe
Keyword(s):  
Phase Locking ◽  
Receptive Fields ◽  
Mechanical Stimulus ◽  
Glabrous Skin ◽  
Mechanical Stimuli ◽  
Sinusoidal Vibration ◽  
Response Level ◽  
Reversible Inactivation ◽  
Stimulus Response ◽  
Cortical Cooling

1. Localized cortical cooling was employed in anesthetized cats for the rapid reversible inactivation of the distal forelimb region within the primary somatosensory cortex (SI). The aim was to examine the responsiveness of individual neurons in the second somatosensory area (SII) in association with SI inactivation to evaluate the relative importance for tactile processing of the direct thalamocortical projection to SII and the indirect projection from the thalamus to SII via an intracortical path through SI. 2. Response features were examined quantitatively before, during, and after SI inactivation for 29 SII neurons, the tactile receptive fields of which were on the glabrous or hairy skin of the distal forelimb. Controlled mechanical stimuli that consisted of l-s trains of either sinusoidal vibration or rectangular pulses were delivered to the skin by means of small circular probes (4- to 8-mm diam). 3. Twenty-three of the 29 SII neurons (80%) showed no change in response level (in impulses per second) as a result of SI inactivation. These included seven neurons activated exclusively or predominantly by Pacinian corpuscle (PC) receptors, six that received hair follicle input, four activated by convergent input from hairy and glabrous skin, and six driven by dynamically sensitive but non-PC inputs from the glabrous skin. 4. Six SII neurons (20%), also made up of different functional classes, displayed a reduction in response to cutaneous stimuli when SI was inactivated. 5. Stimulus-response relations, constructed by plotting response level in impulses per second against the amplitude of the mechanical stimulus, showed that the effect of SI inactivation on individual neurons was consistent over the whole response range. 6. The reduced response level seen in 20% of SII neurons in association with SI inactivation cannot be attributed to direct spread of cooling from SI to the forelimb area of SII, as there was no evidence for a cooling-induced prolongation in SII spike waveforms, an effect that is known to precede any cooling-induced reduction in responsiveness. 7. As SI inactivation produced a fall in spontaneous activity in the affected SII neurons, we suggest that the inactivation removes a source of background facilitatory influence that arises in SI and affects a small proportion of SII neurons. 8. Phase-locking and therefore the precision of impulse patterning were unchanged in the responses of SII neurons to vibration during SI inactivation. This was the case whether response levels of neurons were reduced or unchanged by SI inactivation.(ABSTRACT TRUNCATED AT 400 WORDS)

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